Voice prosthesis

ABSTRACT

A voice prosthesis for vocal rehabilitation of laryngectomees and which includes an air bypass valve assembly having a valve body with a port communicating with the atmosphere for inhalation and exhalation of air. A tube is connected to the valve body and has an end adapted to be inserted in a tracheostomy opening in the human neck. A second tube is connected to the valve body with its end adapted to be inserted in a cervical esophageal fistula. The second tube has a check valve for preventing reflux of secretions from the esophagus into the valve body. The valve body includes a valve member which assumes a first position providing communication between the port and the opening during breathing at normal or stomal levels so that inhalation and exhalation normally are accomplished through this port. The valve member is movable in response to the increased breathing levels necessary for phonation into a second position in which the port is closed to the atmosphere so that air exhaled from the lungs at phonation levels is transmitted from the tracheostomy opening via these tubes and the esophageal fistula to flow over the esophageal mucosa in the area of the cricopharyngeus and provide a sound source that is articulated for speech.

United States Patent 1 1 Taub [451 July 24, 1973 VOICE PROSTHESIS Stanley Taub, Brooklyn, N.Y.

[73] Assignee: New York Medical College, New

York, N.Y.

[22] Filed: Nov. 1, 1971 [21] Appl. No.: 194,179

[75] Inventor:

52 Us. (:1. 3/1.3, 128/351 511 1111. Cl. ..A61f 1/20 58 Field of Search 3/1, 1.3; 128/351; 179/1 AL [56] References Cited UNITED STATES PATENTS 3,017,880 I l/1962 Brook 128/351 X 3,137,299 6/1964 Tabor 128/351 2,304,076 8/1957 Giraudon 128/351 2,405,850 8/1946 Roberts 3/1.3

FOREIGN PATENTS 0R APPLICATIONS 1,207,144 8/1959 France 128/351 716,079 10/1966 Italy 128/351 Primary Examiner--Richard A. Gaudet Assistant Examiner-Ronald L. Frinks Attorney-Stuart N. Senniger et a1.

[57] ABSTRACT A voice prosthesis for vocal rehabilitation of laryngectomees and which includes an air bypass valve assembly having a valve body with a port communicating with the atmosphere for inhalation and exhalation of air. A tube is connected to the valve body and has an end adapted to be inserted in a tracheostomy opening in the human neck. A second tube is connected to the valve body with its end adapted to be inserted in a cervical esophageal fistula. The second tube has a check valve for preventing reflux of secretions from the esophagus into the valve body. The valve body includes a valve member which assumes a first position providing communication between the port and the opening during breathing at normal or stomal levels so that inhalation and exhalation normally are accomplished through this port. The valve member is movable in response to the increased breathing levels necessary for phonation into a second position in which the port is closed to the atmosphere so that air exhaled from the lungs at phonation levels is transmitted from the tra- V cheostomy opening via these tubes and the esophageal fistula to flow over the esophageal mucosa in the area of the cricopharyngeus and provide a sound source that is articulated for speech.

18 Claims, 5 Drawing Figures VOICE PROSTHESIS BACKGROUND OF THE INVENTION This invention relates to voice prostheses and more particularly voice prostheses for vocal rehabilitation of laryngectomees.

The loss of speech following a laryngectomy procedure is a severe functional and social impairment that is not easily overcome. With the aid of speech therapy, many laryngectomees can develop an effective esophageal voice. But esophageal speech as a substitute for the lost laryngeal voice is low in volume, difficult to produce, requires an extensive learning process which 1 many cannot master, and is lacking in the smoothness and ease of production inherent in the natural laryngeal voice. Thus even those who are trainable to use this 1 speech substitute may refrain from doing so to avoid being noticed. Moreover, many laryngectomees are not able to learn to use this substitute for the natural voice and the silence thus imposed constitutes a severe and permanent disability.

A number of artificial larynxes have been proposed and used over the years. Typically they utilized a vibrating metal reed, the sound from which is transmitted directly into the oral cavity through a rubber tube introduced into the mouth. Also, electrically powered devices were introduced in which sound was generated and then transmitted through the cervical soft tissues into the pharynx. Several surgical or operative procedures have also been devised to enable laryngectomees to speak. These include the forming of an internal skinlined tube between the pharynx and the trachea. Typical of some of the prior-art artificial larynxes and speech-facilitating attachments are those shown in U.S. Pat. Nos. 1,836,816, 1,867,350, 1,985,013, 2,198,241 and 3,066,674.

Generally, however, prior artificial larynxes or speech-facilitating devices have not been fully satisfactory. Most were bulky or cumbersome and required the use of one hand of the laryngectomee, offered little if any better sound that that produced by esophageal voice inasmuch as there was little variation in pitch or intensity of the produced sound, were complex electrically and/or mechanically and required frequent repair and maintenance, or were difficult to use. The surgical techniques or procedures tended to be complex and involved and problems were encountered because of the reflex of food and secretions into the trachea thereby causing respiratory problems.

SUMMARY OF THE INVENTION Among the several objects of this invention may be noted the provision of a voice prosthesis which permits the laryngectomee to attain a more natural manner of speech and allows speech with inflection and excellent volume; the provision of such a voice prosthesis which permits the laryngectomee free use of his hands and requires no external power supply but utilizes only the laryngectomee's own respiratory system; the provision of a voice prosthesis which does not have to be removed during eating and in which the reflux of food and secretions into the unit and into the trachea are prevented; the provision of such a voice prosthesis which is easily concealed below the clothing such as a shirt collar and is thus not visible to others; the provision of a voice prosthesis which is relatively simple in construction and is reliable in operation; and the provision of a method of vocal rehabilitation of laryngectomees which requires only relatively simple surgical techniques and procedures and which requires little or no training to use effectively and which produces substantially natural speech effortlessly. Other objects and features will be in part apparent and in part pointed out hereinafter.

Briefly, the voice prosthesis of this invention includes an air bypass valve assembly having a valve body with a port communicating with the atmosphere for inhalation and exhalation of air. A first tube is connected to the valve body, having its end adapted to be inserted in a tracheostoma of a laryngectomee. A second tube is connected to the valve body with its end adapted to be inserted in a cervical esophageal fistula. The valve body has a valve member which assumes a first position in which there is communication between the port and the tracheostoma or tracheostomy opening during breathing at normal or stomal levels so that inhalation and exhalation at these levels are accomplished via this port. The valve member is movable in response to increased breathing levels necessary for phonation into a second position in which the port is closed to the atmosphere whereby air exhaled from the lungs at phonation levels is transmitted from the tracheostomy opening via the first tube and the second tube through the esopha' geal fistula to flow over the esophageal mucosa in the area of the cricopharyngeus to provide a sound source that is articulated for speech. In the method of this invention, wherein laryngectomees having a tracheostoma formed during the laryngectomy are rehabilitated vocally, a cervical esophageal fistula is formed and the laryngectomee is then fitted with an external tracheoesophageal bypass between the tracheostoma and the fistula. A valved port is interposed in this bypass to provide communication between the tracheostoma and the atmosphere so as to permit the laryngectomee to inhale and exhale at stomal levels via the port and to block the port during exhalation at phonation levels. In the latter blocked port condition during phonation, air is thus transmitted from the lungs via the tracheostoma, the external bypass and the fistula to flow over the esophageal mucosa in the area of the cricopharyngeus and to provide a sound source that is articulated for speech.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation of a voice prosthesis of this invention as worn by a laryngectomee;

FIG. 2 is a view of the voice prosthesis of FIG. 1 with portions shown in cross section to illustrate details of certain internal structure and parts;

FIG. 3 is a cross section on line 3-3 of FIG. 2

' through the valve body of a voice prosthesis of this invention;

FIG. 4 is a cross section of an alternate check valve for the esophageal fistula entry portion of this voice prosthesis; and

FIG. 5 is an elevation of a voice prosthesis valve body of an alternate embodiment of this invention, illustrat ing in cross section the internal details of a breathpowered sound generator.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS Referring now to the drawings, a voice prosthesis for vocal rehabilitation of laryngectomees is illustrated generally at reference numeral 1. This prosthesis, shown worn by the laryngectomee so as to rest in the general area of the natural hollow at the front of the throat, includes an air bypass valve V having a generally cylindrical valve body 3 with a tubular boss 5 extending downwardly (as shown in FIGS. 1-3 and 5) and receiving a tubular control member 7. This valve body and its component parts are preferably fabricated from synthetic resin materials such as polycarbonate to provide a clear, lightweight, tough and strong structure. Control member 7 has a tubular stem 9 having a beveled inner end 11, which constitutes a valve seat, and an enlarged outer end or knob 13. Stem 9 is rotatable in the boss 5 and a seal is provided therebetween by an O-ring 15. This rotatable tubular control means has a central bore 17 which serves as a port or first passage to provide communication between the atmosphere and the interior of valve V. A flexible resilient flappertype valve member 19 is secured at its lower edge as indicated at 21 to an internal ledge 22 within valve body 3. This flapper valve 19 is generally circular and preferably formed from thin (e.g., about 0.03 inch) silicone rubber sheet and is biased by its own resilience to the solid-line position shown in FIG. 2 so as to overhang valve seat 11 but be spaced therefrom. Also provided within valve body 3 is a generally D-shaped stop 23 positioned on the side or surface of the valve member 19 opposite that facing seat 11.

Valve V is interposed in an external tracheoesophageal bypass including a first rubber or plastic tube 25 connected to a nipple 26 providing a second passage in communication with valve seat 11 projecting from valve body 3 and having its end connected to a nipple 27 secured to extend angularly from an end flange 28 of a conventional tracheotomy or laryngectomy tube 29 (which is inserted in the tracheostomy opening or tracheostoma customarily surgically formed in the laryngectomees neck), and a second rubber or plastic tube 30. Tube 30 is connected to another valve body nipple 31 providing a thirdpassage in the valve body in communication with the second passage (nipple 26) and has its other end connected to an external fistula check valve F which in turn has a tubular outlet nipple 33 inserted into the belled outer end of a rubber or plastic tube 34 extending through a cervical esophageal fistula. The tubes 25 and 30 are preferably of the reinforced type having a wire helix encased in the tubing to provide some stiffness and resistance to sharp bending and collapse. The cervical esophageal fistula is formed by the surgeon in the laryngectomees neck by making a longitudinal incision paralleling the anterior border of the sternomastoid muscle and carried deeply between the sternal and clavicular heads anterior to the carotid sheath into the retroesophageal space. An opening is made into the lateral wall of the esophagus at a level approximating C4-C5 (4th and 5th cervical vertebrae) large enough to admit the tip of the little finger. This opening is made as low as feasible so that a rotated skin flap raised from the lateral side of the original incision may be rotated to lie in a retrograde direction. By plastic surgical techniques, a skin-lined esophageal fistula is thereby formed which slants downwardly into the esophagus.

It is important that snug seals be maintained between both ends of the tracheoesophageal bypass and the tracheostoma and fistular surfaces to prevent air and fluid leakage. Thus in some instances where leakage problems are encountered some means, such as small inflatable endotracheal cuffs, may be worn over the portions of the laryngectomy and the fistula tubes at their entry points. Also, the tracheostomy tube is typically provided with a plate 35 with slots 36 to which end clips of a collar (not shown) may be attached to secure and support the prosthesis.

With the voice prosthesis worn as shown in FIG. 1, valve member 19 will maintain substantially its first or solid-line position as the laryngectomee breathes at normal or stomal levels (typically at pressures of 7-10 cm. of water). Thus inhalation and exhalation at this level take place via the port or passage 17. When the laryngectomee wishes to speak, he increases his breathing level to that normally necessary for phonation (typically pressures of 15-20 cm. of water) and the differential air pressure on the opposite sides of valve member 19 causes it to move to its second or dashed-line position closing the passage 17 and thereby causing the air exhaled from the lungs at phonation levels to be transmitted through tube 30 and to be delivered through the esophageal fistula to flow over the mucosa in the area of the cricopharyngeus and provide a sound source that is articulated by the tongue, teeth, palate and lips for speech. This flow of air into the upper end of the esophageus and pharynx causes the walls of the cricopharyngeus and the hypopharynx to vibrate to produce a tone of varying pitch which can be articulated as noted above. As the valve member 19 in its first position is clear of the seat (FIG. 1) to such an extent as to provide a passage between the seat and valve member in communication with port 17 of a cross sectional area not substantially less than that of the port, inhalation and exhalation at stomal levels are substantially unrestricted and unobstructed. Thus the laryngectomee can breathe freely at normal levels via the port 17 and only at phonation levels, and automatically, is exhalation directed through tube 30 to flow air from the trachea via the tracheostomy opening into the hypopharnyx. Stop 23 prevents excessive movement of valve member 19 away from the valve seat.

This prosthesis may be adjusted to the different breathing levels of different individuals by rotating knob 13 and thereby varying the attitude of the seat 11 relative to the surface of valve member 19. As the plane of the beveled end seat is rotated, this varies the air pressure to which the valve member 19 responds for movement into its second position to close port 17. This may be easily adjusted by the laryngectomee so that when he exercises or engages in some strenuous activity he may turn the knob to an open position to permit greater exchange of air and then readjust it again during more normal activities.

Fistula valve F includes a two-piece valve body of, for example, clear plastic material with an inlet housing 37 having a nipple 39 to which the exit end of tube 30 is attached and an internally threaded boss 41 into which a second outlet housing portion 43 is threaded. A centrally grooved seat 45 is provided at the base of the threaded boss section 41. A spider ring 47 is held snugly against this seat and sealed relative thereto by means of an O-ring 49 when the two housing portions 37 and 43 are fully threaded together. A flutter valve diaphragm 51 of silicone rubber or the like (e.g., 0.02 inch thick) and having an integral central stem 53 is secured to the downstream side ofring 47. Stem 53 has an enlarged head portion 57 which is pushed through a central hub 55 and expands to retain the centermounted valve diaphragm 51 within the valve body. This diaphragm has sufficient body or stiffness to normally assume a closed or solid-line position as shown in FIG. 2 and thus prevent reflux of food particles or secretions into tube 30 and valve V. However, during phonation the pressure of the exhaled air transmitted as shown by the dashed-line arrows through tube 30 and valve F will cause flutter valve 51 to assume its dashed-line open position, thus permitting the exhaled air to pass virtually unimpeded into the fistula valve housing section 43 and out nipple 33 thereof and through the esophageal fistula tube 341.

An alternate type of fistula valve FA is illustrated in FIG. 4. As contrasted with fistula valve F which is mounted externally, valve FA is a check valve mounted on the distal end of a tubular extension 59 of rubber or plastic which extends through the fistula to project into the esophagus. A resilient flexible valve diaphragm 61 is secured to the top edge of the beveled end of extension 59 which constitutes the valve seat. The diaphragm 61, of natural rubber or silicone rubber or the like, has sufficient body to remain in its closed or solidline position except during exhalation at phonation lev els, whereupon it opens to its dashed-line position.

While the above-described voice prosthesis is effective in the vocal rehabilitation of most laryngectomees, the anatomical characteristics of a few of them may be such that the esophageal mucosa has insufficient resilience to vibrate at sufficient amplitude and/or the esophagus is not normally narrowed at the sphincter level. In such exceptions, a different sound source is desirable and the embodiment of FIG. 5 includes a breath-powered reed component to provide a sound source or generator G to modulate the air transmitted into the hypopharynx. This vibratory reed generator rs located in the upper (as viewed in the drawings) portion of the valve body of the air bypass valve and is in communication with tube 30. The modified valve VA has a valve body 3A with an upper portion constituting a sound generator casing 63 formed integrally therewith and having an entrance chamber 65, a flat reed 67 secured at its upper end to an abutment 69 of casing 63, and a sound chamber 71. The frequency of this sound generator may be adjusted by means of a screw 73. This sound generator component of this alternate voice prosthesis may, for example, be constructed as described in U.Sl Pat. No. 1,836,816. Valve body 3A also includes a pair of tubular extensions 75 and 77 which serve as traps to receive any moisture or fluid that may be collected or form in tubes 25 and 30, respectively, and a pair of caps 79 and 811 which may be removed occasionally for draining and cleaning the valve body.

In operation, this embodiment functions in a fashion quite similar to that of the embodiments of FIGS. ll-4l except that the air supplied or transmitted through the esophageal fistula tube is sound modulated, typically at a low (e.g., about 120-180 cps.) frequency, and flows into the esophagus and provides a sound source that is articulated for speech.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A voice prosthesis for vocal rehabilitation of laryngectomees comprising an air bypass valve assembly including a valve body having a port communicating with the atmosphere for inhalation and exhalation of air, a first tube connected to said body with its end adapted to be inserted in a tracheostomy opening in a human neck, a second tube connected to said body with its end adapted to be inserted in a cervical esophageal fistula, said valve body having a valve member which assumes a first position in which there is communication between said port and said tracheostomy opening during breathing at stomal levels whereby inhalation and exhalation are accomplished via said port and which is movable in response to increased breathing levels necessary for phonation into a second position in which the port is closed to the atmosphere whereby air exhaled from the lungs at phonation levels is transmitted from the tracheostomy opening via said tubes and the esophageal fistula to flow over the esophageal mucosa in the area of cricopharyngeus and provide a sound source that its articulated for speech, said second tube including a check valve for preventing reflux of secretions from the esophagus into the valve body, the operation of said valve assembly being substantially insensitive to the effects of gravity, said valve member when in its first position being clear of the seat to such an extent as to provide a passage between said valve member and said seat in communication with said port of a cross sectional area not substantially less than that of said port whereby inhalation and exhalation at stomal levels are substantially unrestricted. I

2. A prosthesis as set forth in claim 1 wherein the check valve is mounted on the distal end of a tubular extension in communication with said second tube adapted to project internally through said fistula, said check valve comprising a valve flapper biased to close off the distal end of said tubular extension except during phonation.

3. A prosthesis as set forth in claim 1 wherein the check valve is positioned in the second tube intermediate the ends thereof to be located exterior said fistula:

4. A prosthesis as set forth in claim 1 which further includes means for adjustment thereof to vary the air pressure to which the valve member responds for movement into its second position to close said port whereby the prosthesis conveniently may be adjusted to accommodate the different breathing levels of different individuals.

5. A prosthesis as set forth in claim 4 wherein said adjustment means includes a tubular control member having an inner end constituting a valve seat for said valve member, and means for varying the attitude of the seat relative to said valve member.

6. A prosthesis as set forth in claim 5 wherein said tubular control means has a central bore which constitutes said port.

7. A prosthesis as set forth in claim 5 wherein said valve member is a flapper valve and the inner end of the tubular control member is beveled, said control member being rotatable in the valve body whereby the plane of the beveled end may be varied relative to an opposing face of the flapper valve.

8. A prosthesis as set forth in claim wherein the valve body includes stop means positioned on the side of the valve member opposite that facing said seat and adapted to prevent said valve member from excessive movement away from the valve seat.

9. A prosthesis as set forth in claim 5 which further includes external means for manually adjusting said tubular control member, said external means comprising a knob on the outside of said valve body.

10. A prosthesis as set forth in claim 1 which further includes a breath-powered sound generator positioned in communication with the second tube and adapted to generate sound waves for transmission through the fistula in response to the passage of air from the tracheostomy opening during periods when the port is closed by the valve member.

11. In a voice prosthesis for vocal rehabilitation of laryngectomees; a valve assembly including a valve body having a passageway adapted to be placed in communication with both the laryngectomees trachea and the laryngectomees hypopharynx, said valve body having a port of a predetermined cross sectional area providing communication with the atmosphere and said passageway for inhalation and exhalation of air, said valve body including a valve seat and a valve member which assumes a first position in which there is communication between said port and said passageway during breathing at stoma] levels whereby inhalation and exhalation are accomplished via said port and which valve member is movable in response to increased breathing levels necessary for phonation into a second position in which the port is closed to the atmosphere whereby air exhaled from the lungs at phonation levels flows into the hypopharynx to provide a sound source that is articulated for speech, the operation of the valve assembly being substantially insensitive to the effects of gravity, said valve member when in its first position being clear of said seat to such an extent as to provide a passage between said valve member and said seat in communication with said port of a cross sectional area not substantially less than that of said port whereby inhalation and exhalation at stoma] levels are substantially unrestricted.

12. In a voice prosthesis as set forth in claim 11, means for adjustment to vary the air pressure to which the valve member responds for movement into its second position to close said port whereby the prosthesis conveniently may be adjusted to accommodate different breathing levels of different individuals.

13. In a voice prosthesis as set forth in claim 12, said adjustment means including a tubular control member having an inner end constituting a valve seat for said valve member, and means for varying the attitude of said seat relative to said valve member.

14. In a voice prosthesis as set forth in claim 13, external means for manually adjusting said tubular control member, said external means comprising a knob on the outside of said valve body.

15. In a voice prosthesis as set forth in claim 14, said tubular control means having a central bore which constitutes said port, said valve member being a flapper valve and the inner end of the tubular control member being beveled, said flapper valve being biased by its own inherent resilience to said first position, said control member being rotatable in the valve body wherein the plane of the beveled end may be varied relative to an opposing face of the flapper valve.

16. In a voice prosthesis as set forth in claim 11, a check valve connected to said valve body for preventing reflux or secretions into said valve assembly.

17. In a voice prosthesis as set forth in claim 16, said check valve including a valve flapper substantially insensitive to the effects of gravity and biased to block communication between the hypopharynx and said valve body except during phonation.

18. In a voice prosthesis as set forth in claim 11, a breath-powered sound generator connected to said valve body adapted to generate sound waves for transmission into the hypopharynx in response to the passage of air from the lungs during periods when the port is closed by the valve member.

W UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,747,1 7 Dated y 1973 lnventor(s) Stanley Taub I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[ Front page, data element 73, the assignee' s name should read: "New York Medical College, Flower and Fifth Avenue Hospitals". Column 1, line ll, "that that" should read "than that"; line 48, "reflex" shouldread "reflux". Column 5, line 37, "rs" should read "is". Column 8, line 29, "reflux or" should read "reflux of".

Signed and sealed; this 29th "day of January 1974.

SEAL) Attest:

EDWARD M.FLETCREB, I RENE D. TEGTMEYER Attestlng O v Acting Commissioner of Patents 

1. A voice prosthesis for vocal rehabilitation of laryngectomees comprising an air bypass valve assembly including a valve body having a port communicating with the atmosphere for inhalation and exhalation of air, a first tube connected to said body with its end adapted to be inserted in a tracheostomy opening in a human neck, a second tube connected to said body with its end adapted to be inserted in a cervical esophageal fistula, said valve body having a valve member which assumes a first position in which there is communication between said port and said tracheostomy opening during breathing at stomal levels whereby inhalation and exhalation Are accomplished via said port and which is movable in response to increased breathing levels necessary for phonation into a second position in which the port is closed to the atmosphere whereby air exhaled from the lungs at phonation levels is transmitted from the tracheostomy opening via said tubes and the esophageal fistula to flow over the esophageal mucosa in the area of cricopharyngeus and provide a sound source that its articulated for speech, said second tube including a check valve for preventing reflux of secretions from the esophagus into the valve body, the operation of said valve assembly being substantially insensitive to the effects of gravity, said valve member when in its first position being clear of the seat to such an extent as to provide a passage between said valve member and said seat in communication with said port of a cross sectional area not substantially less than that of said port whereby inhalation and exhalation at stomal levels are substantially unrestricted.
 2. A prosthesis as set forth in claim 1 wherein the check valve is mounted on the distal end of a tubular extension in communication with said second tube adapted to project internally through said fistula, said check valve comprising a valve flapper biased to close off the distal end of said tubular extension except during phonation.
 3. A prosthesis as set forth in claim 1 wherein the check valve is positioned in the second tube intermediate the ends thereof to be located exterior said fistula.
 4. A prosthesis as set forth in claim 1 which further includes means for adjustment thereof to vary the air pressure to which the valve member responds for movement into its second position to close said port whereby the prosthesis conveniently may be adjusted to accommodate the different breathing levels of different individuals.
 5. A prosthesis as set forth in claim 4 wherein said adjustment means includes a tubular control member having an inner end constituting a valve seat for said valve member, and means for varying the attitude of the seat relative to said valve member.
 6. A prosthesis as set forth in claim 5 wherein said tubular control means has a central bore which constitutes said port.
 7. A prosthesis as set forth in claim 5 wherein said valve member is a flapper valve and the inner end of the tubular control member is beveled, said control member being rotatable in the valve body whereby the plane of the beveled end may be varied relative to an opposing face of the flapper valve.
 8. A prosthesis as set forth in claim 5 wherein the valve body includes stop means positioned on the side of the valve member opposite that facing said seat and adapted to prevent said valve member from excessive movement away from the valve seat.
 9. A prosthesis as set forth in claim 5 which further includes external means for manually adjusting said tubular control member, said external means comprising a knob on the outside of said valve body.
 10. A prosthesis as set forth in claim 1 which further includes a breath-powered sound generator positioned in communication with the second tube and adapted to generate sound waves for transmission through the fistula in response to the passage of air from the tracheostomy opening during periods when the port is closed by the valve member.
 11. In a voice prosthesis for vocal rehabilitation of laryngectomees; a valve assembly including a valve body having a passageway adapted to be placed in communication with both the laryngectomee''s trachea and the laryngectomee''s hypopharynx, said valve body having a port of a predetermined cross sectional area providing communication with the atmosphere and said passageway for inhalation and exhalation of air, said valve body including a valve seat and a valve member which assumes a first position in which there is communication between said port and said passageway during breathing at stomal levels whereby inhalation and exhalation are accomplished via said port and which valve member is movable in response to increased breathing levels necessary for phonation into a second position in which the port is closed to the atmosphere whereby air exhaled from the lungs at phonation levels flows into the hypopharynx to provide a sound source that is articulated for speech, the operation of the valve assembly being substantially insensitive to the effects of gravity, said valve member when in its first position being clear of said seat to such an extent as to provide a passage between said valve member and said seat in communication with said port of a cross sectional area not substantially less than that of said port whereby inhalation and exhalation at stomal levels are substantially unrestricted.
 12. In a voice prosthesis as set forth in claim 11, means for adjustment to vary the air pressure to which the valve member responds for movement into its second position to close said port whereby the prosthesis conveniently may be adjusted to accommodate different breathing levels of different individuals.
 13. In a voice prosthesis as set forth in claim 12, said adjustment means including a tubular control member having an inner end constituting a valve seat for said valve member, and means for varying the attitude of said seat relative to said valve member.
 14. In a voice prosthesis as set forth in claim 13, external means for manually adjusting said tubular control member, said external means comprising a knob on the outside of said valve body.
 15. In a voice prosthesis as set forth in claim 14, said tubular control means having a central bore which constitutes said port, said valve member being a flapper valve and the inner end of the tubular control member being beveled, said flapper valve being biased by its own inherent resilience to said first position, said control member being rotatable in the valve body wherein the plane of the beveled end may be varied relative to an opposing face of the flapper valve.
 16. In a voice prosthesis as set forth in claim 11, a check valve connected to said valve body for preventing reflux or secretions into said valve assembly.
 17. In a voice prosthesis as set forth in claim 16, said check valve including a valve flapper substantially insensitive to the effects of gravity and biased to block communication between the hypopharynx and said valve body except during phonation.
 18. In a voice prosthesis as set forth in claim 11, a breath-powered sound generator connected to said valve body adapted to generate sound waves for transmission into the hypopharynx in response to the passage of air from the lungs during periods when the port is closed by the valve member. 